Putting antibiotic use in perspective

As the debate over antibiotic use in animal agriculture heats up, a common claim from opponents is that 80 percent of antibiotics sold in the United States are used in animals. This, they say, supports the accusation that agricultural use is a primary cause of emergence of antibiotic-resistant pathogens. However, in an opinion piece published in Food Safety News, Richard Raymond, a medical doctor and former undersecretary for food safety at the U.S. Department of Agriculture, brings some perspective to the statistics thrown around in the antibiotics discussion.

In his column titled “Antibiotics and Animals Raised for Food: Lies, Damn Lies and Statistics,” Dr. Raymond says the 80 percent number is meant to be a distraction from the real truth. The numbers reported by the FDA reflect total volume of antibiotics sold, but do not indicate how the products were used.

More importantly, the 80 percent figure lumps all types of antibiotics together. Citing a report from the FDA, Raymond details the reasons the figure is misleading. First, 28 percent of all antibiotics sold for use in animals in 2010 were ionophores, a class of drugs never approved for use in human medicine. Once accounting for other drugs not approved for human use, the total percentage of antibiotics sold for use in animals but not used in human medicine reaches 45 percent.

Tetracycline, he says, was the class of antibiotics most widely used in animals in 2010. In the past, tetracycline was widely used in human medicine, but today accounts for just 1 percent of the volume of antibiotics sold for human use.

So, Raymond writes, 87 percent of antibiotics used in animals are either never, or very rarely, used in human medicine.

In contrast, the cephalosporin and the fluoroquinolone classes of antibiotics accounted for 24 percent of antibiotics sold for use in humans in 2009, but represented just 0.3 percent of those sold for use in animals.

Raymond also notes that antibiotic resistance is not a new phenomenon. Cases of resistant pathogens turned up just seven years after the introduction of penicillin in 1943, and just one year after the introduction of methicillin in 1959. Emergence of bacteria resistant to those drugs, he says, occurred because of their use in humans, not animal agriculture.